The glomeruli of the kidney perform the key role of blood filtration. Each functioning glomerulus consists of a tuft of capillaries and several types of cells, and is surrounded by a Bowman's capsule forming the corpuscle. The number of glomeruli in a kidney is correlated with susceptibility to chronic kidney and cardiovascular disease, driving interest in technology to measure glomerular morphology. Cationic ferritin nanoparticles have been used to target, image, and count individual glomeruli in the whole kidney with magnetic resonance imaging (MRI). Accumulated nanoparticles create spots in MR images at each glomerulus. However, previous techniques have been unable to perform fast, reliable measurements of glomeruli in the image. Accordingly, improved techniques are desirable.